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Computed Tomography Angiogram (CT Angiogram)

Test Overview

A
computed tomography angiogram (CT angiogram) is a test
that uses
X-rays to provide detailed pictures of the heart and
the blood vessels that go to the heart, lung, brain, kidneys, head, neck, legs,
and arms.

A CT angiogram can show whether a blood vessel is
blocked, where the blockage is, and how big the blockage is. The test can also
show whether there is a bulge (aneurysm) or a buildup of fatty
material called
plaque in a blood vessel.

During a CT
angiogram, you lie on a table that passes through a doughnut-shaped opening in
the scanner. A special dye (contrast material) is put in a vein
(IV) in your arm or hand to make the blood vessels
easier to see on the scan. If you are having a CT angiogram to look at your
heart and the blood vessels that go to it (coronary arteries), you may be given a medicine called a
beta-blocker to slow your heart rate during the
test.

Why It Is Done

A CT angiogram is done to look
for:

A narrowing (stenosis) or blockage in the coronary arteries. This
can occur when there is a buildup of fat (cholesterol)
and calcium in the arteries. This buildup is called plaque.

Heart
problems, such as
pericarditis (a buildup of fluid around the heart) and
damage or injury to the heart valves.

A bulge (aneurysm) or tear
(dissection) in the
aorta, which is a large blood vessel that carries
blood from the heart to the rest of the body.

How To Prepare

Before you have a CT angiogram, tell your
doctor if you:

Are or might be pregnant.

Are
breast-feeding. You will need to use formula (not your breast milk) for 1 to 2
days after the CT angiogram until the dye has passed from your body. Or you can
pump your breast milk and store it before the test and use that for a couple of
days.

Are allergic to any medicines, including iodine
dyes.

Have a heart condition, such as
heart failure.

Have
diabetes or take metformin (such as Glucophage) to
control your diabetes.

Have a history of kidney
problems.

Have
asthma.

Have a history of
thyroid problems.

Have had
multiple myeloma.

Have had an
X-ray test using barium contrast material (such as a
barium enema) in the past 4 days. Barium shows up
on X-ray films and makes it hard to see the picture clearly.

Become very nervous in small spaces. You will
have to lie still inside the CT scanner, so you may need a medicine (sedative)
to help you relax. If you are given a sedative, you may need to have someone
take you home after the test.

You may be asked not to eat or drink anything for several
hours before the test. Your doctor will let you know if there are certain foods
or liquids you should avoid.

Talk to your doctor about any concerns
you have regarding the need for the test, its risks, how it will be done, or
what the results will mean. To help you understand the importance of this test,
fill out the
medical test information form(What is a PDF document?).

How It Is Done

A CT angiogram is usually done by a
radiology technologist. The pictures are usually read
by a
radiologist. But some other types of doctors may also
review the test results.

Before the test

Take off any jewelry and any other metal
objects.

Take off all or most of your clothes. You will be given a
gown to wear during the test.

During the test

You will lie very still on a table that is
attached to the CT scanner.

A dye (contrast material) will be put
in a vein in your arm or hand. If you are having a CT angiogram to look at your
heart and the blood vessels that go to it (coronary arteries), you may be given
a medicine called a beta-blocker to slow your heart rate during the
test.

The table will slide into the round opening of the scanner
and move slightly while the scanner takes pictures. You may hear a click or
buzz as the table and scanner move.

The technologist may ask you to
hold your breath for a few seconds at a time.

You may be alone in
the scanning room. But the technologist will watch you through a window. You
will be able to talk to him or her through an intercom.

A CT angiogram usually takes 30 to 60 minutes but could
take up to 2 hours.

After the test

Drink plenty of fluids for 24 hours after the test to help flush the dye
out of your body.

How It Feels

A CT angiogram is not painful. The table
you lie on may feel hard, and the room may be cool. It may be hard to lie still
during the test.

When the dye is given, you may:

Feel a brief sting or pinch from the needle
going into your vein.

Feel warm and flushed.

Feel sick
to your stomach or get a headache.

Have a metallic taste in your
mouth.

Tell the technologist or your doctor how you are
feeling.

Risks

The risk from having a CT angiogram is small. But
some risks include:

Exposure to radiation. There is a slight chance
of developing cancer from some types of CT scans.1 The
chance is higher in children, young women, and people who have many radiation
tests. If you are concerned about this risk, talk to your doctor about the
amount of radiation this test may give you or your child. Make sure that the
test is needed.

An
allergic reaction to the dye (contrast material). But
this is rare, and most reactions are mild and can be treated with medicine.

Kidney problems. The dye used during the test can cause kidney
damage in people whose kidneys don't work well.

The dye may also cause problems for people who take
metformin (such as Glucophage) to control their diabetes. Your doctor will tell
you when to stop taking metformin and when to start taking it again after the
test so you won't have a problem.

Results

Results of a CT angiogram are usually ready for your doctor in 1 to 2 days.

Computed tomography angiogram

Normal:

The blood vessels look normal,
and blood flow is not reduced.

The heart and heart valves look
normal.

No narrowing, blockage,
bulging (aneurysm), or large buildup of
plaque is seen.

A narrow spot in an artery may
suggest that a blood clot or a deposit of fat and calcium is reducing blood
flow through the blood vessel.

An abnormal pattern of blood
vessels may be a sign that a tumor is present.

What Affects the Test

You may not be able to have a CT
angiogram if:

You are pregnant. A CT angiogram isn't usually
done when a woman is pregnant, because there is a chance that the baby might be
harmed by the radiation.

You have had an X-ray test that used
barium
contrast material (such as a
barium enema) in the past 4 days. Barium shows up on
a CT angiogram and makes it hard to see the picture clearly. A CT angiogram
should be done before any tests that use barium.

You are
allergic to the dye (contrast material) that is used during the
test.

You have kidney problems. The dye used during the test can
cause kidney damage in people whose kidneys don't work well.

You
take metformin (such as Glucophage) to control your
diabetes. The dye used during the test may cause
problems if you take this medicine.

You are obese. A person who is
very overweight may not fit into a standard CT machine, or the X-ray table may
not be able to support his or her weight.

You can't lie still
during the test.

You have metal objects in your body, such as
surgical clips or metal in joint replacements. These objects may prevent a
clear view of the areas being examined.

What To Think About

Benefits and limitations

A CT angiogram is a less
invasive test than a standard angiogram. A standard angiogram involves
threading a thin tube called a catheter through an artery in your arm or leg up
to the area being studied. But with a CT angiogram, no tubes are put in your
body. To learn more, see the topic
Angiogram.

If your doctor sees that one
or more of your blood vessels are blocked, you may need a standard angiogram
anyway to double-check the abnormal results from the CT angiogram. This is more
likely to happen if your doctor is considering surgery to treat the
blockage.

If your doctor finds a major blockage in one of your
blood vessels during a CT angiogram, you won't be able to get an immediate
angioplasty to clear the blockage. You will need a
separate procedure. But if you have a standard angiogram and the doctor finds a
major blockage, he or she can perform an angioplasty during the
angiogram.

Certain things can make CT angiograms hard to read. For
example, a fast heart rate may make it hard to get a clear picture of the
coronary arteries. Or a large buildup of calcium may
show a narrowing of the arteries when there isn't one (false-positive)
or show that the arteries are fine when they are not (false-negative). But with a standard angiogram, these
things don't interfere with the test.

Other tests

Another test, called a coronary calcium scan, also uses a CT scan to show how much calcium is in your coronary
arteries. This test is for people who have no symptoms of heart disease but may be at risk for getting it. To learn more, see the topic
Coronary Calcium Scan.

CT technology

If your doctor suggests a CT
angiogram, you may want to ask what kind of scanner will be used. In most
cases, a 16– or 64–multi-slice (or multi-detector) CT scanner is used for the
CT angiogram. These scanners provide more detailed images of the blood vessels
and organs in less time than other imaging tests. But they may not be available
in all medical centers.

Other Works Consulted

Bluemke, D, et al. (2008). Noninvasive coronary artery
imaging: Magnetic resonance angiography and multidetector computed tomography
angiography. A scientific statement From the American Heart Association
Committee on Cardiovascular Imaging and Intervention of the Council on
Cardiovascular Radiology and Intervention, and the Councils on Clinical
Cardiology and Cardiovascular Disease in the Young. Circulation, 118: 586–606.

Budoff M, et al. (2006). Assessment of coronary artery
disease by cardiac computed tomography: A scientific statement from the
American Heart Association Committee on Cardiovascular Imaging and
Intervention, Council on Cardiovascular Radiology and Intervention, and
Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation, 114(16): 1761–1791.

Taylor AJ, et al. (2010). ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 – Appropriate use criteria for cardiac computed tomography: A Report of the American
College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society of Cardiovascular Computed Tomography, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the American Society of Nuclear Cardiology, the North American Society for Cardiovascular Imaging, the Society for Cardiovascular Angiography and Interventions, and the Society for Cardiovascular Magnetic Resonance. Journal of the American College of Cardiology, 56(22): 1864–1894.

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